What do the Scriptures say about defense?
I went searching for a verse about weapons or defense and found only these:
Whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man. - Genesis 9:6
Thou shalt not kill. - Exodus 20:13
In other words, we were made in God's image - our lives are valuable. He does not want us to kill, yet He doesn't want us to give up ours too easily either. Weapons are necessary for defense as there are always enemies and evil afoot. There are several references to people carrying weapons for self-defense in the Scriptures. See Luke 22:35-39, for example, where Jesus said: "he who has no sword, let him sell his garment and buy one." Weapons were also used for hunting.
On the same note, remember that Christ laid down His life, while He could have been saved by legions of angels (Luke 22:51). He hates "the wrong And the one who loves violence". (Psalm 11:5).
Our God is a god of love and a god of justice. Vengeance is His. No weapons formed against Him shall prosper. (See Isaiah 54:17)